In Bluetooth®, a network includes a master node which performs polling control for communication timing control and access control of a communication device, and a slave node which performs communication in accordance with a signal from the master node. One master node and at most seven slave nodes can construct a network as referred to as a piconet. In order to connect the communication device belonging to the Bluetooth® network to an Ethernet® LAN, an access point serves as the master node, and the communication device connected to the network serves as the slave node. In Bluetooth®, a frequency hopping spread spectrum scheme is used. In the piconet, time division multiplex (time division slot multiplex) is performed for each slot. And a plurality of nodes in the piconet can communicate with each other. Since a slot synchronous state must be maintained, all the nodes in the piconet have counters called Bluetooth clocks. In one piconet, in order to match the Bluetooth clock value of the slave with that of the master, a clock offset which is a shift between the Bluetooth clock values of the slave node and master node is calculated. Accordingly, the clock synchronous state can be maintained by adding (subtracting) the offset value to (from) the Bluetooth clock value of the slave node. The nodes in a single piconet have the same frequency-hopping pattern. Hence, the nodes can communicate with each other.
Bluetooth® defines the following arrangement (to be referred to as a scatternet hereinafter). When the communication device currently connected to the access point (a piconet) is to join another piconet (e.g., a new piconet including a communication device such as a PC), the communication device shifts to a power-saving mode in which intermittent reception is temporarily performed in communication with the master node (in this case, the access point) which controls the current piconet. Then, the connection with the access point is released, and communication is performed after switching to the communication timing of the new piconet.
In a Bluetooth® piconet operation, the communication devices (slave nodes) communicate with each other via the master node which controls an access timing. Accordingly, the traffic increases in a wireless section, and data cannot be efficiently transferred. In the scatternet operation described as a unit for avoiding this problem in the prior art, access-timing control for a specific slave node (to be referred to as a slave 1) is performed by determining the access timing in accordance with the power-saving mode timing set between the slave 1 and master node which operate asynchronously. Hence, the initially set access time cannot be ensured in accordance with clock frequency shift between the master nodes.
When the communication traffic between the slave 1 and the master, and the communication time between the slave 1 and another master are to be changed, a power-saving mode shift time between the master and the slave 1 must be reset. Hence, it is difficult to sequentially accommodate the access time in accordance with the change in the traffic. As a means for solving this problem, a method of notifying of a period (communication deterrence period) in which the slave capable of joining the plurality of piconets does not join the piconet has been studied. However, a method of notifying the master of the communication deterrence period has not been disclosed yet, and it is difficult to perform access control in accordance with a communication state such as the traffic.
As described above, in a wireless communication scheme in which one wireless communication node can belong to the plurality of wireless networks at the same time, a timing for accessing/inaccessing to each of the networks must be arbitrated. However, this arbitration is difficult.